Throughout the day, Chellis said dispatchers and callers couldn't hear each other during some 911 calls and the seven-digit non-emergency calls to police.

"At times we've had issues with a particular trunk or switch at the central office," Chellis said. "But this is the most serious and longterm outage we've had in the system since its inception in 1993."

Verizon is the main provider for the county's system.

Verizon, TW Telecom and Cassidian technicians worked on the problem all day.

Verizon is still investigating what caused the failure.

During the outages, emergency services employed their backup system and provided callers another number to speak with dispatchers.